The following abbreviations that may be found in the specification and/or the drawing figures are defused as follows:
3GPP Third Generation Partnership Project
CDM Code Division Multiplexing
CMAS Commercial Mobile Alert System
D2D Device-to-Device
DL Downlink
DRX Discontinuous Reception
eNB Evolved Node B/Base Station in an EUTRAN System
EUTRAN Evolved UTRAN (LTE)
ETWS Earthquake and Tsunami Warning System
FDD Frequency Division Duplex
FDM Frequency Division Multiplexing
ID Identification
IMSI International Mobile Subscriber Identity
IP Internet Protocol
ISM Industrial, Scientific, Medical
LTE Long Term Evolution
LTE-A Long Term Evolution Advanced
MME Mobility Management Entity
PDCCH Physical Downlink Control Channel
PDSCH Physical Downlink Shared Channel
PF Paging Frame
PO Paging Occasion
P-RNTI Paging Radio Network Temporary Identifier
RRC Radio Resource Control
SFN System Frame Number
SIB System Information Block
TDD Time Division Duplex
TDM Time Division Multiplexing
UE User Equipment
UL Uplink
UTRAN Universal Terrestrial Radio Access Network
The device-to-device (D2D) communication may enable new service opportunities and reduce the eNB load for short range data intensive peer-to-peer communications. Qualcomm has proposed a study item for the D2D in 3GPP TSG-RAN #52 plenary, 31 May-3 Jun. 2011, e.g., see Tdoc-RP-110706, “On the need for a 3GPP study on LTE device-to-device discovery and communication”, Qualcomm Incorporated, 3GPP TSG-RAN #52, Bratislava Slovakia May 31-Jun. 3, 2011; Tdoc-RP-110707, “Study on LTE Device to Device Discovery and Communication—Radio Aspects, “Qualcomm Incorporated, 3GPP TSG-RAN #52, Bratislava Slovakia May 31-Jun. 3, 2011; Tdoc-RP-110708, “Study on LTE Device to Device Discovery and Communication—Service and System Aspects,” Qualcomm Incorporated, 3GPP TSG-RAN #52, Bratislava Slovakia May 31-Jun. 3, 2011.
One of the main targets is to evolve the LTE platform in order to intercept the demand of proximity-based applications by studying enhancements to the LTE radio layers that allow devices to discover each other directly over the air, and potentially communicate directly, when this makes sense from a system management point of view, upon appropriate network supervision.
The 3GPP TSG-RAN #52 document Tdoc-RP-110706, cited above, states as follows: “This radio-based discovery process needs also to be coupled with a system architecture and a security architecture that allow the 3GPP operators to retain control of the device behavior, for example who can emit discovery signals, when and where, what information do they carry, and what devices should do once they discover each other.”
Heterogeneous local communication plays also a vital role in the future wireless networking as can be ascertained from recently published press releases of the Qualcomm's FlashlinQ concept (http://www.cedt.iisc.ernet.in/people/kuri/Comsnets/Keynotes/Keynote-Raiiv-Laroia.pdf, last visited on Oct. 21, 2011).
It can be assumed that the D2D discovery is also to be supported in RRC_IDLE state in which there is no RRC connection towards the eNB but the device has a valid IP address, it has been authenticated and its security context is stored in the MME. RRC_IDLE mode provides an opportunity to have power efficient state for low duty cycle discovery and service advertisement signaling by the D2D devices while being authenticated by the serving network (which should allow autonomous signal transmission on certain resources).
To receive paging messages from EUTRAN, UEs in RRC_IDLE mode monitor the PDCCH channel for a P-RNTI used to indicate paging. The UE only needs to monitor the PDCCH channel at certain UE-specific occasions (i.e., at specific subframes within specific radio frames. At other times, the UE may apply DRX, meaning that it can switch off its receiver to preserve battery power.
Radio/physical layer D2D discovery method for RRC_IDLE mode anticipates UEs to wake up during both D2D discovery resource and paging occasions. It means that the UE's paging channel occurs in a different frame than D2D discovery resources requiring the second UE to wake up listening to different frames at different times.
Paging in LTE system in 3GPP TS 36.304 V10.1.0, “User Equipment (UE) procedures in idle mode” is described as follows:
“One Paging Occasion (PO) is a subframe where there may be P-RNTI transmitted on PDCCH addressing the paging message. One Paging Frame (PF) is one Radio Frame, which may contain one or multiple Paging Occasion(s). When DRX is used the UE needs only to monitor one PO per DRX cycle.
PF and PO is determined by following formula using the DRX parameters provided in System Information:
PF is given by following equation:SFN mod T=(T div N)*(UE—ID mod N)Index i_s pointing to PO from subframe pattern will be derived from following calculation:i—s=floor(UE—ID/N)mod Ns 
T: DRX cycle of the UE. T is determined by the shortest of the UE specific DRX value, if allocated by upper layers, and a default DRX value broadcast in system information. If UE specific DRX is not configured by upper layers, the default value is applied.
nB: 4T, 2T, T, T/2, T/4, T/8, T/16, T/32.
N: min(T,nB)
Ns: max(1,nB/T)
UE_ID: IMSI mod 1024.”
The 3GPP TS 36.331 V10.0.0, “Radio Resource Control (RRC)” describes that in RRC_IDLE mode, the UE monitors a Paging channel to detect incoming calls, system information change, for ETWS capable UEs, ETWS notification, and for CMAS capable UEs, CMAS notification.
The 3GPP TS 36.331 V10.0.0, “Radio Resource Control (RRC)” describes that in RRC_CONNECTED mode, the UE Monitors a Paging channel and/or System Information Block Type 1 contents to detect system information change, for ETWS capable UEs, ETWS notification, and for CMAS capable UEs, CMAS notification.